The effect of resistance training on quadriceps muscle volume and some growth factors in elderly and young men.

Aging process is associated with loss of muscle mass, strength and growth factors dysfunction. Resistance training is one of the effective methods to overcome a decline in muscle mass, strength and also can modulate the level of myostatin, follistatin and insulin-like growth factor-1 (IGF-1) factors. The purpose of this study was to investigate the effect of 8 week resistance training on different anabolic factors which influence muscle hypertrophy in elderly and young men. Fifteen elderly and sixteen young men volunteered and participated in a periodized 3-day per week progressive resistance training program for a total of 8 weeks. Daily calorie intake, muscle volume, cross-sectional area (by computed tomography) and myostatin, follistatin, IGF-1, growth hormone (GH) and testosterone were calculated before and after the training protocol. At the end of the training period, the strength in the elderly group increased significantly compared to the young group (p<0,05); no differences of daily nutrient intake were found in both groups (p>0,05). Quadriceps muscle volume and cross-sectional area increased more in the younger group (p<0,05). Myostatin concentration significantly decreased in both groups (p<0,05), yet the amount of change was not different in either groups (p>0,05). Follistatin and testosterone increased in both groups (p<0,05), but growth hormone and IGF-1 increased in the younger group only (p<0,05). Resistance training improved hypertrophy and lead to anabolic conditions in elder and young subjects, but in different ways. In this regard, GH-IGF-1 axis and growth factors profile at the baseline had an important role in different age-related hypertrophy.

The Effect of Gold Nanoparticles on Electrical Impedance of Tissue on Low Frequency Ranges.

INTRODUCTION: Electrical impedance of tissues on low frequencies includes useful information about functional and structural changes in tissues. This property is used in Electrical Impedance Tomography (EIT) imaging modality for the detection of lesions in tissues. OBJECTIVE: The goal of this article is to study changes in electrical impedance of tissues in the presence of gold nanoparticles. MATERIALS AND METHODS: Spherical gold nanoparticles with size of 20-25 nm were synthesized with Turkevich method. Size distribution and shape of nanoparticles were characterized by transmission electron microscopy (TEM). Electrical impedance of two types of phantoms (chicken fat and muscle paste tissues) was measured by 4-electrode method with and without gold nanoparticles. RESULTS: Results demonstrate a reduction in electrical impedance of tissues in the presence of gold nanoparticles. However, this reduction is not the same for fat and muscle tissues. Reductions in resistive impedance are 40.24Ω and 1.93 Ω for fat and muscle tissues on the frequency of 1 KHz, respectively. A reduction in electrical impedance is accompanied by a rise in electrical conductance leading to increase in EIT signal. CONCLUSION: As signal enhancement is different for fat and muscle tissues; presence of gold nanoparticles could be used to improve EIT image contrast.